Important UNIX Commands!!

Important UNIX Commands!! 

Please find below important UNIX commands   which we generally use in our day to day activities.

du –kh

To get disk usage in Megabytes

du –k | sort –n | tail -10

Shows the ten largest files/directory

awk 'END{print NR}' file_name

To get number of lines in any file

awk '{print $1}' file_name

To print first column of the file

cat /dev/null > file_name or cp /dev/null file_name

Make content zero of the file

tar –cvf file_name.tar file_name

Make tar of any file or directory (tar – tape archive)

tar –xvf file_name.tar

Extract contents of any tar file or directory

lsof -i TCP|PORT_NUMBER or lsof –i | grep PORT_NUMBER

Mapping port with process

pargs PID

To know the process name by using PID

Glance or top or prstat –a or vmstat

To know memory utilization

prtconf | grep Mem

Display Memory Size of the machine

isainfo –bv

To check out whether machine is in 32 or 64 bit mode

last

To know who was or still is on the system

psrinfo

To know about the processors

psrinfo | wc –l

To know total number of processors

uname –a or uname -X

Display system information

who –b

To display the date and time of last reboot

grep PATTERN FILE_NAME

To print all the lines from file this is having this pattern like   grep e-business SystemOut.log

gzip FILE_NAME

It will compress the file and save with .gz extension like   file_name.gz

gunzip file_name.gz

It will decompress the file.

hostname

It will give you the name of machine which you are using.

netstat –an | grep PORT_NUMBER

To know port is listening or not

ps –ef | grep java

To get PID of all java process

lsof –i | grep PORT_NUMBER

To get PID of port number

pargs PID

To get process name corresponding to this PID

find DIRECTORY_PATH -name "*.*" | xargs grep ""   PATTERN

To find out any particular pattern in all files inside any directory

find DIRECTORY_PATH -name 'FILE_NAME' | xargs perl -pi -e   's/SOURCE_PATTERN/DESTINATION_PATTERN /g'

To replace any particular pattern with new pattern in any file in   specific directory

history

Display recent commands

who

shows who is logged into the local system

find DIRECTORY_PATH -name FILE_PATH -print

To find out any particular file inside any directory and its sub   directory